Manufacturing a complex composite structure, such as for example in the fabrication of an aircraft or large portions of an aircraft, require a large number of composite parts to be separately fabricated and secured together. With fabricating a large number of composite parts, there needs to be close adherence to tolerances for each of those parts in order for the parts to fit to adjacent parts, for the parts to optimally secure to one another and to provide a desired shape for the completed complex composite structure.
Once the individual parts are fabricated, the parts need to be assembled and fastened together to complete the complex structure. Fasteners are used to secure together the composite parts in fabricating the complex composite structure. Use of fasteners adds manufacturing steps such as drilling and installation of the fastener assemblies and which also add weight to the finished complex composite structure. The employment of fasteners not only adds to labor costs associated with installation of the fasteners but in some instances where a fastening is applied locations are created in which sealant may need to be applied. Composite parts can be bonded together, but the testing requirements for satisfying the FAA requirements are sufficiently burdensome that this mode of securement is generally avoided for the primary structure of an aircraft. Also, when bonding is employed for assembling a complex composite structure frequently fasteners are also used.
There is a need to be able to fabricate complex composite final structures where the need for bonding or use of fasteners is eliminated. In addition, there is a need to reduce the occurrence of exposing carbon fibers. With drilling holes into composite parts in order to employ fasteners for securing the parts, the drilling undesirably exposes the fibers of the composite material. Carbon fibers of composite material are more electrically conductive than the resin of the composite material. Exposed carbon fiber ends are sources of sparks during high voltage events such as a lightning strike. As a result, carbon fibers requires sealing so as to prevent sparking and any fuel ignition. In an example of fabrication of complex structures, such as in the manufacturing of an aircraft, there is a need, as mentioned above, for reducing expensive sealing operations. Sealing operations are required, for example, in joining and securing separate parts in the fabrication of items such as a fuel tank. There is also a need to avoid the added weight, cost, manufacturing process and manufacturing time to an aircraft that occurs in providing, for example, access holes in the wing boxes used in a fuel tank sealant process. In addition, there is a need to reduce the occurrence of deformation of a composite structure as a result of the curing process.